From those cities, 38 have started a water rationing plan, where the supply is alternated between neighborhoods every week. One of the most concerning situations, however, is in São Paulo city, the state capital and Latin America’s largest metropolis. The Cantareira System, a four-lake complex of reservoirs responsible for providing water to 45 percent of the city’s metropolitan area (about 6.5 million people) and other surrounding cities, is now running at record lows of 4.1 percent of its total capacity.

Some people believe they're going through unofficial rationing. On the website Faltou Água (Water was missing), a collaborative map shows locations where users have reported interruptions to their water supply.

Below is a selection of the messages posted to the website in August and September:

Most of the population of the city of São Paulo STILL doesn't feel the water shortage (and believes in the state government, and keeps wasting water and making jokes on the subject) for a simple reason: they live in apartment buildings. When Sabesp cuts off the supply (every day), they keep getting water from their taps and think it's all good. But this water is coming from the building's water tower, which is collective. As some apartments use less water than others, they naturally compensate each other. But that will last only if there's still water in the collective tank.

Since May, the company has been using the first quota of the “dead volume” (the remnants of water that lie in the bottom of the lake). Regulators had prohibited it from collecting from the second quota of that volume over concerns it was mismanaging supplies, but that decision was revoked yesterday due to the emergency of the situation, since the first quota will only last for the next few weeks.

The second quota comprises of 106 billion liters and should last until March 2015 without water rationing. After that, it is over: there is no “third” dead volume quota at the Cantareira. All there is left is to hope that the rainfall during the wet season, which peaks in December through February, will be enough to provide more water for the rest of 2015.

The state government's plan is only this: to drain the reservoirs until the last drop and to pray it will rain. There is no plan B. That being said, I think it's time we recognize something: the time to think about the rational and conscious use of water is over. That ship has sailed. The main discussion now is not “use it wisely so it won't end”. It is ending nonetheless – or, if we consider we've been consuming the “dead volume” water, it has ended already.

There are 38 municipalities in the countryside who are going through official water rationing. Those cities are not attended by Sabesp, but rather have their water supplied by small, local companies.

The main advantage of going through an official rationing is that people are able to know when and at what time they’ll have their water interrupted – so they can take precautions and are not caught by surprise.

That doesn’t necessarily prevent rallies and revolts, though. Itu, a city with 163,000 inhabitants, has experienced rationing since February and has been supplied poorly, with the district having to buy 3 million liters of water daily from nearby cities. On Sunday, residents attended a fourth rally against the water shortage, blocking a highway and setting fire to a bus.